The unseen source: Importance of groundwater-coastal water interactions
THURSDAY, OCTOBER 11, 2012 - 3:30 PM IN EIT 3142 AT THE UNIVERSITY OF WATERLOO
Abstract:
Canada has the world's longest coastline extending along the Pacific, Atlantic and Arctic Oceans, and also along the shores of the Great Lakes. Pollution of coastal waters is an increasingly serious problem due to rapid urbanization, intensification of agriculture and industry and increasing pollutant toxicity. While the contribution of surface water inputs on coastal water pollution is generally well characterized, the groundwater pathway is often poorly understood. Predicting groundwater-derived pollutant loading rates is complex as loading is controlled not only by the specific pollutant sources, groundwater flow paths but also by biogeochemical transformation processes occurring near the sediment-water interface. Oceanic forcing (tides and waves) create complex and dynamic fluxes across the sediment-coastal water interface and this leads to the creation of important biogeochemical zonations that strongly control the fate of discharging pollutants. Numerical modeling simulations will be presented that illustrate the impact of tides on the transport, transformation and subsequent discharge of groundwater-derived chemicals including nutrients and BTEX contaminants. Field data collected on a sandy beach on the Great Lakes which isolates the effect of waves on the subsurface transport and accumulation of heavy metals (e.g., arsenic, iron) in nearshore beach sediment will also be discussed.